2 km ESE of Eureka, Missouri

2021-04-20 08:38 UTC · 19 km deep · released about 150 lb of TNT

Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.

When: 2021-04-20 08:38 UTC
Magnitude: M 2.5 (md)
Depth: 19 km below the surface
Felt: 474 reports · strongest reported intensity V
Nearest: St. Louis County, 22 km NE
Status: Reviewed by a seismologist

USGS · last changed by USGS 1390 days ago · we first saw it 1390 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage. 474 people have reported feeling it to USGS.

How big was it?

This earthquake released about 150 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.5 would have released about 32 times as much.

Mineral, Virginia 2011 M 5.8 100,000× the energy of this one
Magna, Utah 2020 M 5.7 72,000× the energy of this one
Around the size people start to feel M 3.0 6.5× the energy of this one
This earthquake M 2.5 about 150 lb of TNT

Energy from the Gutenberg–Richter relation (log₁₀E = 1.5M + 4.8), rounded to two figures; bar length is magnitude, which is already a logarithm of energy. Magnitudes of past earthquakes from the USGS catalogue.

Where

Map loads when it scrolls into view

Epicentre 38.4902, -90.6028. Map © OpenStreetMap contributors.

Nearby places

Place	Distance	Direction
St. Louis County, MO	22 km (13 mi)	SW of here	earthquakes near St. Louis County
Jefferson County, MO	26 km (16 mi)	NNW of here	earthquakes near Jefferson County
St. Charles County, MO	33 km (20 mi)	S of here	earthquakes near St. Charles County
St. Louis city, MO	35 km (22 mi)	WSW of here	earthquakes near St. Louis city
Franklin County, MO	42 km (26 mi)	ENE of here	earthquakes near Franklin County
Monroe County, IL	44 km (27 mi)	WNW of here	earthquakes near Monroe County

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

8 earthquakes have been recorded within 50 km since this one.

2.0 6 km SSW of Valmeyer, Illinois 02:23 UTC
2.4 3 km ESE of Fenton, Missouri 10:27 UTC
1.7 3 km WNW of Olympian Village, Missouri 21:37 UTC
2.3 4 km S of Valmeyer, Illinois 00:00 UTC
2.3 4 km E of Herculaneum, Missouri 23:37 UTC
2.6 1 km S of Old Monroe, Missouri 08:30 UTC
2.5 eastern Missouri 02:32 UTC
2.8 1 km SSW of Peerless Park, Missouri 22:30 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 07:25 UTC. QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.

On USGS

The official USGS event page — the source of record for every value above
Did you feel it? Report it to USGS — reports go to USGS, not to us
ShakeMap for this event, when USGS has produced one

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.